Autonomic Nervous System Flashcards
purpose of sensory aspect of CNS
receptors detect internal or external stimuli and relay information to the CNS through afferent neurons
purpose of integrative aspect of CNS
analysis, storage, decision making, perceptions using interneurons
purpose of motor aspect of CNS
muscular contraction, glandular secretion through efferent neurons
two types of fibres of afferent divsion of CNS
- somatic afferent fibres
- visceral afferent fibres
somatic afferent fibres
carry impulses from skin, skeletal muscles and joints
visceral afferent fibres
transmit impulses from visceral organs
two systems that fall under the efferent divsion of the CNS
- somatic nervous system
- autonomic nervous system
purpose of somatic nervous system
provides conscious control of skeletal muscles
purpose of autonomic nervous system
regulates cardiac and smooth muscle and secretory glands
what is the PNS
nervous structures outside the brain and spinal cord that are not covered in meningeal layers
two aspects of PNS
cranial nerves and spinal nerves
how many pairs of cranial nerves are there
12
where do cranial nerves I & II attach to
forebrain
where do cranial nerves III-XII attach to
brainstem
how many pairs of spinal nerves are there
31
how many pairs of cervical spinal nerves
8
how many pairs of thoracic spinal nerves
12
how many pairs of lumbar spinal nerves
5
how many pairs of sacral spinal nerves
5
how many pairs of coccygeal spinal nerves
1
why are there 8 cervical spinal nerves
- cervical nerves exit spinal foramina above their vertebra
- thoracic nerves exit spinal foramina below their vertebra
- thus there is an extra cervical nerve above T1
what are ganglia
oval shaped collections of neuronal cell bodies found in autonomic and somatic branches of PNS
another name for preganglionic cells
presynaptic neurons
where are the cell bodies of the preganglionic neurons located
in the grey matter of the CNS
another name for postganglionic neurons
postsynaptic neurons
where are the cell bodies of postgangliomic neurons located
within the autonomic ganglia
where do the axons of postsynaptic neurons terminate
effector muscles and organs (cardiac/smooth muscle and glands)
pathway of preganglionic axons from spinal cord
- exit spinal cord and enter spinal nerve
- exit spinal nerve via white communicating ramus
- enter sympathetic trunk/chain
three paths that a preganglionic axon can take after entering sympathetic chain
- immediately synapse on postganglionic neuron in chain ganglion then return to spinal nerve and follow its branch to the skin
- ascend/descend within spinal cord before proceeding as above
- pass through sympathetic chain without synapsing, form a splanchnic nerve that passes towards thoracic or abdomincal organs. These synapse in prevertebral ganglion in front of aorta, post ganglionic axons follow arteries to organs
where are sensory ganglia found
in dorsal root ganglia of spinal nerves and on the ganglia of some cranial nerves
purpose of dorsal root ganglia of spinal nerves
sensory
transmit messages relating to pain, touch and temperature from the PNS to the CNS
purpose of sensory ganglia of cranial nerves
- have special sensory functions
- eg. trigeminal ganglion: contains sensory nerve fibres from head
name the three groups of autonomic ganglia
- sypathetic chain ganglia
- prevertabral ganglia
- parasympathetic ganglia
what is the sympathetic chain ganglia
paired chain of ganglia located ventral and lateral to the spinal cord that extends from upper neck to coccyx
how many pairs of ganglia are there in the sympathetic chain/trunk
23
purpose of sympathetic trunk
- recieve input from lateral horn of thoracic and lumbar spinal cord
- relay information relating to stress and anger
where are prevertebral ganglia located
between sympathetic chain and target organs
prevertebral ganglia purpose
carry sympathetic function but are not part of sympathetic chain
innervate all abdominal and pelvic organs (excluding adrenal gland)
where are parasympathetic ganglia located
in the cranial nerve nuclei and lateral horn of sacral spinal cord
another name for sypathetic nervous system and why
thoracolumbar system - preganglionic neuronal cell bodies are located in the lateral horn of grey matter from T1-L2
sympathetic nervous system purpose
- mobilisation and increased metabolism
- fight, flight or freeze
fibre lengths in sympathetic nervous system
- short preganglionic fibres
- long postsynaptic fibres
where are postsynaptic nerurons of the sympathetic nervous system present
paravertebral and prevertebral ganglia
what neurotransmitter is associated with the sympathetic nervous system
noradrenaline or norepinephrine
another name for the parasympathetic nervous system and why
craniosacral system - preganglionic neuronal cell bodies are in the brain stem or sacral levels of the spinal cord
parasympathetic nervous system function
- routine maintenance
- rest and digest
where are the fibres of the parasympathetic nervous system found
- cranial nerves III, VII, IX & X
- lateral horn of grey matter S2-S4
fibre length for parasympatheric nervous system
long preganglionic fibres and short postsynaptic fibres
what does the parasympathetic nervous system supply
head, visceral cavities of the trunk and erectile tissues of the external genitalia
what neurotransmitter is associated with the parasympathetic nervous system
acetylcholine
